1. Field of the Invention
The invention relates to leak detection methods and apparatus. More specifically the invention is a method and apparatus for detecting leaks across an O-ring sealing a flanged end of a pipe, container or the like.
2. Discussion of Background and Prior Art
O-rings and gaskets are well known as sealing mechanisms between two surfaces such as the flanged ends of pipe sections, the flanged top of a container and its lid, or other mating surfaces. O-rings are usually made of a resilient substance such as rubber or plastic that deform as the two mating surfaces are brought together. A shallow groove is usually provided to hold the O-ring in place and direct its deformation.
To verify that an O-ring has formed a tight seal, various tests have been devised. Sometimes soap is spread on the outside of the piping or container at the interface of the two mating surfaces and air is pumped from within. Soap bubbles caused by escaping air betray the leaks.
For high vacuum systems, helium is used because of its mobility. Helium is sprayed on all the joints to test for leaks. Because helium moves readily through air, false positive indications are frequent as the helium finds other paths to the detector.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method and apparatus for improving the detection of leaks across O-ring seals.
It is a further object of the present invention to provide a method and apparatus for eliminating false positive indications of leaks across O-ring seals.
It is a still further object of the present invention to provide a method and apparatus allowing an O-ring seal to be checked for leaks at any time.
To achieve the foregoing and other objects and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention comprises an improvement to a flange at the end of piping section or the top of a container to be mated with another surface and which flange has an O-ring in a circumferential groove, the improvement comprising a second groove, or channel, in the surface of the flange adjacent to and following the circumference of the O-ring and an entrance port to and an exit port from the second groove. Injecting a leak detection fluid such as helium in the entrance port as the leak detection fluid is withdrawn from the exit port so that a flow of fluid is created in the second groove allows the fluid to circulate in the second circumferential groove and have access to the O-ring for leak detection. If the presence of helium is detected on the other side of the O-ring, it may be presumed that a leak in the O-ring exists.
Because the helium is directed at the O-ring by the second groove, the present invention does not miss any leaks and is much quicker than the present practice. Only a small burst of helium will serve to show a leak across the O-ring, not enough helium to affect background levels in the testing environment where other joints may also be undergoing testing, and the test can be done at any time without disturbing the seal connection.
Reference is now made in detail to the present preferred embodiment of the invention, an example of which is given in the accompanying drawings.